Distance measurement device, distance measurement method, and radar device

A distance measurement device comprising:

• processing circuitry
• to divide a digital signal into N digital signals (N is an integer equal to or greater than 2), the digital signal showing interference light between reflected light which is received from a distance measurement target by applying part of frequency swept light whose frequency varies with time to the distance measurement target, and reference light which is the remaining part of the frequency swept light;
• to shift a frequency of each of the N digital signals after distribution by a shift amount, the plurality of shift amounts of frequencies for the corresponding N digital signals being different from each other;
• to perform a Fourier transform on each of the N digital signals after frequency shift;
• and
• to determine a frequency component related to the distance measurement target, out of a plurality of frequency components contained in all of N signals after the Fourier transform,
• to determine a shift amount from the plurality of shift amounts after the Fourier transform, the determined shift amount being related to a signal which includes the determined frequency component and is associated with one of the N digital signals, and
• to calculate a distance from the distance measurement device to the distance measurement target from a sum of a frequency of the determined frequency component and the determined shift amount.